1. Field of the Invention
The present invention relates to an apparatus for programmably converting an operating voltage of a CPU and chipset, and more particularly to an apparatus for programmably converting an operating voltage of a CPU and chipset by means of a firmware, instead of by a jumper.
2. Description of Related Art
Recently, with the increase of computer manufacturers and the differences of their manufacture techniques, the specifications of operating voltages of the central processing units (CPU) and the chipset have become various. For example, for a Pentium.RTM. (Pentium.RTM. is a registered trademark of Intel Corporation) CPU used in a personal computer, the operating voltages of the CPUs manufactured by INTEL, CYRIX and AMD are different. Even though the CPUs are produced by one manufacturer, they are distinct. For instance, the SSS numbered in a back of the Pentium.RTM. CPU indicates an operating voltage of 3.3 volts and the VMU indicates an operating voltage of 3.45 volts. While a CYRIX CPU has the operating voltages such as 3.3 volts and 3.52 volts according to its number. Also, a high frequency CPU requiring a voltage regulation module (VRM) has the operating voltages such as 2.5 volts and 2.7 volts. Consequently, to support above mentioned CPUs, the manufacturers have to provide a plurality sets of jumpers or built-in voltage converters within a computer for users to adjust the operating voltage of the CPU and the chipset.
FIG. 1 shows a schematic view of a conventional regulation circuit. The conventional regulation circuit comprises a DC to DC converter 10, a feedback resistor Rf and a fixed resistor R1. Said feedback resistor Rf and the fixed resistor R1 form a resistance multiplying circuit for enabling the output voltage Vout to input a reference voltage Vref, through the multiplying circuit, to the DC to DC converter 10, thereby to change the resistance of the feedback resistor Rf, the reference voltage Vref and thus the output voltage Vout of the DC to DC converter 10. To send out a group of various voltages from above mentioned structure, a set of jumpers cooperating with resistors of different resistances are used in the regulation circuit, which is the most popular method used nowadays. As shown in FIG. 2, which shows a schematic view of a conventional multistage regulation circuit according to above method, the regulation circuit uses three feedback resistors 21 each connected in series with a jumper set 22. By this arrangement, various feedback resistances are obtained and the operating voltage can be changed.
It is understood that this kind of apparatus and method has several disadvantages. One is that a series of steps such as disassembling the computer, comparing with the handbook and adjusting the jumper or switch are required when the operating voltage is desired to be adjusted. A second disadvantage is that using the jumper for selectively skip connecting may cause an error set. A third disadvantage is that the metal jumper may be aged and oxidized due to humidity and may cause a defective contact. Therefore, there is a need for above apparatus to be improved.
The present invention provides an improved apparatus for programmably converting the operating voltage of a CPU & chipset to mitigate and/or obviate the aforementioned problems.